J., I have a lot of experience with this from dealing with my younger son, and he is NOT autistic. LOTS of kids without autism have speech and language delays.
Yes, you need to get him an evaluation. The expectations after 24 months are very different from before 24 months. Go ahead and get the appointment for right after his 2 year birthday. Ask them to send you the paperwork a week in advance. You should take time to fill out the paperwork very thoroughly. It should ask what words he knows - a lot of detail. Really pay attention to it. It's important, and MUCH better to do it at home than be under the gun filling it out at the center.
A team approach to an evaluation is much better than only one speech therapist, though of course, it's okay not to have the team approach - having had both, I prefer the team approach for a child this age.
It is amazing the strides a child can make with a little help. I promise you that his ability to handle school later will be greatly improved and increased if he has some help before he gets there. If there IS a problem, and you won't know until they have worked with him some, the difference in handling it before he's 3 will make a big difference.
For the kids out there who were just late bloomers, that's one thing. A problem is another, J.. You and your ped can't actually say which it is, and no one on a question and answer site can either. The way to know is to have him properly screened.
I hope you will do it.
Dawn